My mechanic checked the chain and guide....he didn't find any damage there. Guesses more likely the sensor was tripped. Also have driven almost 600 kilometers since the weekend repair- car runs beautifully.

@RJ_RS_SS_350:
When we check the spark plugs, they were almost black, so they needed changing anyway. I've done almost 200K in almost 4 years, so while there might be a little life left in them, better change them then while we were already in there.

As for the RESTORE instructions, they really should be putting better (or more specific) instructions on their bottles before people use it. While usually doing some research before buying something and putting it in my car is kosher- at the same time, I shouldn't have to refer to a website when buying something off-shelf. Other products like Lucas and STP have more and better instructions on their product that you could read and evaluate on the spot before buying and using it. So putting it in, and seeing my engine essentially run like $#!+ immediately after adding is idiotic and unacceptable.

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As for my current mechanic (& family friend), I trust his service and judgement with my life. He's done a number of other cars for me, and he's rarely ever wrong.
I've gone to other mechanics before him, or have had to resort to other mechanics while he's on vacation, and there is simply no comparison.

When you find a good mechanic, you hold onto him for dear life. Believe me, there are those that will give you the run-around, and/or wouldn't hesitate to screw you over. (i.e. A few years ago, my former '93 Caddilac STS car at a former mechanic because of constant engine overheating. After almost 4 months and over $3000 (my student loan for that year) later, the car still ran like crap and burned gas insanely).

 

Yeah...i agree. Might switch to exclusively synthetic oil after this.
Also saw some other post on this site, to add Shell premium v-Power gasoline once a month too- instead of wasting money on fuel additives. Might start to adopt that practice.

 

 

Just thought I'd provide an update to my past situation here.
Car mileage currently at 390K and still going strong. Never had to change the spark plugs or touch timing chain since. Probably will hit 500K in the next 18 months.
Also, after further reading, VVT engines and ANY additives are a bad combination. They do mess up sensors and can potentially damage engine because timing is super-important.
This is probably why I've never had an issue when adding them to any of my prior cars which had non-VVT engines:
-1994 Oldsmobile Cutlass Ciera (gave up @ ~240,000K)
-1993 Saturn SL2 (gave up @ ~240,000K)
-2003 Pontiac Grand AM (gave up @ ~120,000K)
-1993 Cadillac STS (crashed @ ~189,000 K)
-2007 Chevy Impala (gave up @ ~363,000 K)

Will really miss this car, when its time for me to give it up. Again, thanks for all the help and input with my issue. This website is a God-send.